All,
There is a release note published for Cisco NSS300 Series Smart Storage Transition From Firmware Version 1.5 to QNAP Version 3.5 .
http://www.cisco.com/en/US/docs/storage/nass/csbcdp/smart_storage/release/notes/Ciscov1.5_to_QNAPv3.5_FW_RNs.pdf
Direct link above. All release notes are published at:
http://www.cisco.com/en/US/products/ps10817/prod_release_notes_list.html